Stable blue writing ink and a dye therefor



Patented Nov. 29, 1949 UNITED THEREFOR William B. Reynolds, Cincinnati, i)hio, assignor to The Parker Pen Company, Janesvllle, Wis., a corporation of Wisconsin 1 No Drawing.

This invention relates to blue azo dyes. I An object of the invention'is to provide new azo dyes suitedfor use in aqueous alkaline inks, particularly alkaline inks for fountain pens, which dyes will, in such"media, have adesirable clear blue color;- will have adequate solubility in such medialto impart a desirable color intensity thereto,andwill have a higher order of stability in such media than is possessed by previously known blue dyes which were in other respects suited for such use.

Blue is, by far, the most popular color for writing inks. Blue dyes suitable for use in neutral or acid aqueous writing inks'are known and widely used. It has become known that aqueous writtinginks containing strong caustic alkalis have important advantages including quick drying by rapid penetration of the writing paper. However, no satisfactory blue dye has heretofore been found which has the required stability in such inks. :One of the best previously known blue dyes for such use is Brilliant Benzo Blue G-BA Conc. (Colour Index #518, Schulz 6th edition #510). However, it has only relative stability in aqueous inks containing caustic alkali and slowly breaks down to a very undesirable pale, dull color when so used.

The present invention comprises-new azo dyes which have a desirable blue color, adequate solubility and a high order of stability in aqueous inks containing caustic alkali, rendering them eminently suited for use in alkaline aqueous writ- Example 1 1 mole of 4,4-diaminostilbene-2,2-disulfonic acid is stirred to a smooth slurry with 2,000 parts of water.

tinued for one hour. The slurryisthen diluted with 2,000 parts of water and. iced to about C.

by the addition of 1,000 to 2,000 parts r ice. The

diaminostilbene disulfonic acid is tetrazotized by the addition of 2 moles of sodium nitrite dissolved in'500 parts of water. An excess of nitrite,

To this slurry is added 5 moles of, -N hydrochloric acid and the .stirringis con- Application February 25, 1946, Serial No. 650,140

6Claims." (Cl. 10022) 2 as indicated by starch-iodide test paper, is maintained for at least one hour prior to coupling. The coupling solution is prepared by dissolving 2.02 moles of SS-acid (1-amino-8-naphthol- 2,4-disulfonic acid) in 3,000 parts of water by the addition of 8 moles of sodium carbonate. The temperature of the solution is adjusted to 10 C. by the addition of ice. The tetrazo solution prepared above is run into the coupling solution over aperiod of one hour and the resultant solution is stirred for an additional two hours.

The disazo dyestufi is precipitated by the addition of sodium chloride, filtered, washed with brine solution and dried in an air-circulating oven at 60 C.

In the above example, K-acid (1-amino-.8- naphthol-4,6-disulfonic acid) may be substituted for SS-acid.

Example 2 1 lrnole of 3,3'-dichlorobenzidine (m,m' a1- chlorobenzidine) is slurried with 1,000 parts of water and 5 moles of 10-N hydrochloric acid.

The slurry is diluted by the addition of 3,000 parts of water and stirred for at least two hours. Ice (about 1500 parts) is added to lower the tem-' perature to about 10 C. The dichlorobenzidine is tetrazotized by the rapid addition of 2 moles of sodium nitrite dissolved in 500 parts of water. The tetrazo solution is stirred for one hour with a definite excess of nitrite and is then clarifie with activated carbon and filter-aid.

'A coupling solution was prepared by dissolving 2.02 moles of K-acid' (1-amino-8-naphthol-4,6- disulfonic acid) in 3,000 parts of water by the addition of 8 moles of sodium carbonate. The

i coupling reaction, isolationof the resulting-\dyeout appreciable effect on the caustic alkali stability of the dyes.

Each of the four dyes obtained as above described produces intense bright blue color in aqueous caustic alkali solutions and has a high order of stability and permanence making it eminently suited for the production of quick drying, Water-fast, blue alkaline writing inks. By way of example, such inks containing one or more of the new dyes of the present invention may be ml? OH N8O3S NaOaS prepared in accordance with the following for- A bright, blue, permanent ink is obtained which maintains its full color strength on storage for an indefinite period of time. It is contemplated that alkaline writing inks made with the above specified dyes are within the scope of my invention.

The numbering system employed in numbering NaOaS the positions on the benzidine nucleus is that commonly used in standard texts such as Organic Chemistry by Paul Karrer, second En lish edition published 1946 by Elsevier Publishlug Company, Inc., New York (see especially page '78).

I claim:

1. A blue dye stable in caustic alkali solution, said dye consisting at least predominantly of a compound Of the structure X2 R1 R1 R2 R Krwherein X1, is one member and X2 the other member of the class consisting of H and SOsNa, and R1 is a member of the class consisting of H and C1, and, when R1 is H, R2 is SOsNa and y is but, when R1 is Cl, R2 is H and y is a single bond, 'said dye being obtained by coupling, in an alkaline solution, two molecular equivalents of a. Y

member of the class consisting of 1-amino-8- naphthol-2,4-disulphonic acid and 1-amino-8- naphthol-4-6-disulphonic acid with one molec-.

ular equivalent of a member of the class consisting of 4,4-diaminostilbene-2,2'-disulphonic acid and 3,3'-dichlorobenzidine.

2. A blue dye stable in caustic alkali solution, said dye consisting at least predominantly of a 10 compound of the structure H0 IfHz H H sgNa Nflhs SOQNB produced by coupling tetrazotized, 4,4'-diaminostilbene 2,2'-disulphonic acid two molecular mo- 'lecular equivalent of l-amino-8-naphthol-2,4-

disulphonic acid.

3. A blue dye stable in caustic alkali solution, said dye consisting at least predominantly of a compound of the structure I HO NH:

produced by coupling tetrazotized 3,3'-dichlorobenzidine with two molecular equivalents of l-amino-8-naphthol-2,4disulphonic acid.

4. A stable blue writing ink comprising an aqueous solution of a caustic alkali and the dye consisting at least predominantly of a compound of the structure Ika 1 11 Xr- H O NH:

r i 1, is one member and X2 the other member of the class consisting of H and SO3Na, and R1 is a member of the class consisting of H and Cl, and, when R1 is H, R2 is SOaNa and y is but, when R1 is Cl, R; is H and y is a single bond; which dye is obtained b coupling, in an alkaline.

solution, two molecular equivalents of a member.

of the class consisting of 1-amino-8-naphthol- 2,4-disulphonic acid and l-amino-8-naphthols 4,6'-disulphonic acid with one molecular equiva-v lent of a member of the class consisting of 4,4'-,

diaminostilbene-ZZ-disulphonic acid and 3,3- dichlorob'e'nzidine.

5. A stable blue writing ink comprising an aqueous solution of a caustic alkali and the dye 5 6 consisting at least predominantly of a compound 6. A stable blue writing ink comprising an of the structure aqueous solution of a caustic alkali and the dye HQN on 110 NH,

@ s Na Na aS NaO S mm which dye is produced by coupling tetrazotized consisting at least predominantly of a compound 4,4'-diaminostilbene-2,2-disulphonic acid two of the structure nm on no NH, NaOzS N=NQQN= s OaNa Naols some molecular equivalents of I-amino-B-naphtholwhich dye is produced by coupling tetrazotized,

2,4-disulphonic acid. 3,3-dichlorobenzidine with two molecular equivalents of l-amino-8-naphthol-2,4-disulphonic acid.

WILLIAM B. REYNOLDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 498,874 Bamman June 6, 1893 511,532 Kothe Dec. 26, 1893 539,699 Moeller May 21, 1895 594,123 Rudolph Nov. 23, 1897 FOREIGN PATENTS Number Country Date 540,455 Great Britain Oct. 17, 1941 OTHER REFERENCES Schultz: Farbstofi Tabellen, 7th ed., vol. 1, page 177.

Certificate of Correction Patent No. 2,489,463 November 29, 1949 'WILLIAM B. REYNOLDS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 24, after the word edition insert #424 7th edition; line 34, for "4,4'-diamino-stilbene-"read 4,4-diamz'nostilbenecolumn 4, line 4, for naphthol-4 read naphthol-4,6-; line 6, for 4,4-diaminostilbeneread 4,4-diaminostilbenelines 21 and 22, strike out molecular; same line 22, for equivalent read equivalents; line 72, for 3,3- read 3,8;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 18th day of April, A. D. 1950.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents. 

